Parents offer unique information and are recognized as the main informants about children's social emotional functioning across time and situations. Inter-parental agreement was analysed with 100 preschoolers (M[subscript age] = 54.94 months) being rated independently by their mothers and fathers, using the Portuguese version of the Preschool and Kindergarten Behaviour Scales -- Second Edition (PKBS-2). Data were analysed according to four levels: index of agreement, index of disagreement, risk level and item analyses. The results indicated a low to moderate inter-parental agreement, with Pearson correlations ranging from .35 to .59. Fathers rated their children as having more social withdrawal problems (unique score that reached statistical significance) than mothers. No differences between mothers and fathers were found in the number of children included in risk level categories. Item analyses showed high similarities between informants concerning social skills and behaviour problems. Relevance of collecting mothers and/or fathers' reports for research and practice purposes are discussed.